1. Field of the Invention
The present invention related to an improved structure for a high efficiency DC motor, in particular, to an improved structure for a high output DC motor with built-in field windings.
2. Description of the Prior Art
A conventional DC motor is essentially composed of a rotor and a stator. The rotor consists of a moving armature core with the armature windings thereon, several brushes and commutators, while the stator consists of several magnetic poles with field windings, several interpoles, a bracket, a yoke, and a housing. A rotating torque is produced in the rotor to rotate it when input current is fed into the armature windings according to fleming""s left hand law. However, there are some inherent shortcomings with a conventional DC motor constructed as such, i,e. worn out of the commutators and brushes due to sparks and abrasion by a large load current which further causes great machine noise and vibration. In addition to this, the armature windings enclosed in the stator cause bad heat dissipation which is further aggravated by insufficient spacing available for installation of the windings.
The above disadvantages greatly restrict efficiency and applicable field of the conventional DC motors that motor manufactures are eager to eliminate.
In view of the above situation, the inventor of the present invention herein conducted intensive research based on many years experience gained through professional engagement in the manufacturing of related products, with continuous experimentation and improvement culminating in the development of the improved structure for a high efficiency DC motor of this invention.
It is an object of the present invention to provide an improved structure for a DC motor with merits of a low starting current, a light weight armature, reduced brush abrasion, good heat dissipation effect, long life and high efficiency by constructing the motor with a non-ferromagnetic base having an anisotropic ferromagnet and a hermetically sealed center shaft installed therein, and en externally connected control unit.
It is another object of the present invention to provide an improved structure for a DC motor with an externally connected brush structure so as to reduce the wearing of commutators and brushes due to sparks thereby minimizing noise and vibration when the machine operates.
It is a further object of the present invention to provide an improved structure for a DC motor to expose the field windings for facilitating heat dissipation and extending available spacing for windings.
It is one more object of the present invention to provide an improved structure for a DC motor which can be cascade controlled along with a power amplification circuit so as to easily control the motor""s rotational direction, and is able to increase the total power output by connecting several motors in series.
For achieving the aforementioned objects, the DC motor of the present invention is provided with a non-ferromagnetic base having an anisotropic ferromagnet and a center shaft installed thereon. Three equally spaced confinement slots are formed around the outer peripheral surface of the non-ferromagnetic base for stacking up laminated silicon steel sheets serving as cores for the field windings thus forming a three split phase with built-in field structured DC motor.
The control unit is composed of a commutator assembly and a hollow stationary base. The commutator assembly further includes a hollow tube body, a center shaft, three commutator segments and three metal rings. The center shaft is an extended portion of the motor shaft which is passing the hollow tube body and supported at the end terminal, while all three commutator segments and metal rings are secured onto the hollow tube body, and then connected each other with conductors. There are two power supply brushes and three output brushes equipped on the hollow base such that the commutator segments and the metal rings are able to align with their corresponding power supply brushes and output brushes when the commutator assembly is set up in the hollow stationary base. With this structure, the motor can be powerfully driven at desired direction by conjoining the control unit with the main motor on the center shaft.